Derotation Apparatus for Treating Spinal Irregularities

ABSTRACT

Treatment of spinal irregularities, including, in one or more embodiments, derotation apparatus and systems that can be used to reduce the rotation of vertebral bodies. Derotation apparatus that may comprise a tube assembly comprising an inner sleeve and an outer sleeve disposed over the inner sleeve. The inner sleeve may have a distal end for attachment to an implant. The tube assembly may further comprise a handle assembly. The tube assembly may further comprise a ball joint assembly disposed between the tube assembly and the handle assembly. The ball joint assembly may comprise a ball joint configured for attachment to a coupling rod.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 12/632,445 filed on Dec. 7, 2009, which isincorporated in its entirety herein.

FIELD OF THE INVENTION

The present disclosure generally relates to treatment of spinalirregularities. In particular, in one or more embodiments, the presentdisclosure relates to derotation apparatus and systems that can be usedto reduce the rotation of vertebral bodies

BACKGROUND

Many types of spinal irregularities can cause pain, limit range ofmotion, or injure the nervous system within the spinal column. Theseirregularities can result from, without limitation, trauma, tumor, discdegeneration, and disease. By way of example, scoliosis and kyphosis areirregularities that can result in a complex, three-dimensional problemwith lateral curvature of the spine and segmental vertebral rotation.Advances in medicine and engineering have provided doctors with aplurality of devices and techniques for correcting these deformities orirregularities.

One technique for treating scoliosis is the Harrington rod. TheHarrington rod operates on a distraction system attached by hooks to thespine that when distracted, straightens the curve in the spine. Untilthe 1970's, the Harrington rod was the preferred method of treatment forscoliosis. Follow-up studies of these rods documented the negativeeffects of using distraction rods alone for correction of spinaldeformities, including “flat back syndrome” and the resultingdegenerative changes in the lower lumbar spine. Other methods ofmanagement, including spinal fixations systems that include segmentalwires, hooks, rods and/or bone fasteners (e.g., pedicle screws) haverevolutionized the treatment of spinal deformities. The advent andavailability of smaller and stronger bone fasteners has further advancedtreatment, allowing for effective application of corrective forces toposterior systems into the high thoracic spine.

Until recently, spinal fixation systems comprising bone fasteners androds were used almost exclusively to correct the lateral curvature ofthe spine, with little attention paid to segmental vertebral derotation,primarily because bone fastener instrumentation did not provide a meansof rotating the individual vertebral bodies. These systems focused onreducing the rod into the bone fasteners and using rod grips and/or insitu benders to translate the rod to restore sagittal and coronal planebalance. While these patients appear to be corrected on an A-P orlateral x-ray, they frequently present with pronounced rib hump, oraxial twisting of the spine, which can result in significant pulmonarycompromise and further degenerative changes in the spine.

Techniques have also been developed to address segmental vertebralrotation caused by irregularities, such as scoliosis. For instance,derotation systems have been used for the treatment of segmentalvertebral rotation. Current derotation systems typically include a tubeor series of tubes that slot over the implant (e.g., pedicle screw) muchlike a counter torque. These tubes allow the surgeon to push on androtate the vertebral bodies away from the instrumentation, which whenapplied to the apex of the deformity, will straighten the lateralcurvature and can reduce some of the individual rotation between bodies.However, this maneuver frequently results in flat back syndrome and,more importantly, very high applied forces to individual screws, whichcan lead to bone fasteners breaching the medial or lateral walls of thepedicle. This leads to loss of fixation at these levels and can resultin paralysis if the breached screws impact the spinal cord. To reducethe force applied to any one screw, derotation systems may link multiplescrews together so that the force of correction is applied over multiplescrews. However, the surgeon typically cannot connect more than twotubes, and the process to connect the tubes is time consuming,confusing, and often requires separate instruments to assemble andtighten the system together. These factors in an already long andcomplex deformity case have limited the impact of derotation systems forposterior spinal fusion procedures.

Thus, there is a need for improved derotation systems that can securelyconnect to implants with efficient coupling to multiple implants.

SUMMARY

An embodiment of the present invention includes a derotation apparatus.The derotation apparatus may comprise a tube assembly comprising aninner sleeve and an outer sleeve disposed over the inner sleeve. Theinner sleeve may have a distal end for attachment to an implant. Thetube assembly may further comprise a handle assembly. The tube assemblymay further comprise a ball joint assembly disposed between the tubeassembly and the handle assembly. The ball joint assembly may comprise aball joint configured for attachment to a coupling rod.

The features and advantages of the present invention will be readilyapparent to those skilled in the art. While numerous changes may be madeby those skilled in the art, such changes are within the spirit of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a derotation apparatus in accordance with oneembodiment of the present invention.

FIG. 2 illustrates an exploded view of a derotation apparatus inaccordance with one embodiment of the present invention.

FIG. 3 illustrates an embodiment of a tube assembly of a derotationapparatus.

FIG. 4 illustrates an embodiment of a derotation apparatus with a tubeassembly in an unlocked position.

FIG. 5 illustrates an embodiment of a derotation apparatus with a tubeassembly in a locked position in accordance with one embodiment of thepresent invention.

FIG. 6 illustrates an embodiment of a derotation apparatus with the balljoints at different rotational angles.

FIG. 7 illustrates an embodiment of a derotation apparatus with one ofthe ball joints oriented at an angled with respect to the derotationapparatus.

FIG. 8 illustrates an exploded front view of a ball joint in accordancewith one embodiment of the present invention.

FIG. 9 illustrates an exploded side view of a ball joint in accordancewith one embodiment of the present invention.

FIG. 10 illustrates an embodiment of a ball joint in an unlockedposition in accordance with one embodiment of the present invention.

FIG. 11 illustrates an embodiment of a ball joint in a locked positionin accordance with one embodiment of the present invention.

FIG. 12 illustrates an embodiment of a coupled derotation system withtwo derotation apparatuses attached on either side of the same vertebralbody.

FIG. 13 illustrates an embodiment of a coupled derotation system withthree derotation apparatuses in an inline arrangement.

FIG. 14 illustrates an embodiment of a coupled derotation system withmultiple derotation apparatuses.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIGS. 1 and 2 illustrate a derotation apparatus 10 in accordance with anembodiment of the present invention. As illustrated, derotationapparatus 10 comprises a tube assembly 20, a ball joint assembly 30, anda handle assembly 40. Tube assembly 20 may comprise an inner sleeve 50and an outer sleeve 60 disposed over inner sleeve 50 with inner sleeve50 having a distal end 70 configured and adapted for attachment to animplant (not illustrated). In an embodiment, the implant may be attachedto a vertebral body. Ball joint assembly 30 may comprise at least oneball joint 80. As illustrated, ball joint assembly comprises two balljoints 80. As will be discussed in more detail below, force may beapplied to handle assembly 40 to derotate the vertebral body to whichthe implant is attached. This should result in reducing the rotationbetween vertebral bodies in a patient's spine. In addition, rotation ofthe vertebral bodies may also straighten curvature of the spine.

Referring now to FIGS. 1-5, tube assembly 20 of derotation apparatus 10will be described in more detail in accordance with one embodiment ofthe present invention. FIG. 3 illustrates tube assembly 20 with balljoint assembly 30 and handle assembly 40 removed. In general, tubeassembly 20 should attach derotation apparatus 10 to the implant (notillustrated). As previously mentioned, tube assembly 20 includes innersleeve 50 and outer sleeve 60 disposed over inner sleeve 50.

Inner sleeve 50 includes distal end 70 configured and adapted forattachment to an implant (not illustrated). In an embodiment (notillustrated), distal end 70 fits over at least a portion of an implant.While not illustrated, the inner surfaces of distal end 70 may includefeatures configured and adapted for attachment to the implant. Forexample, distal end 70 may include a connection that when allows forcoupling the inner sleeve 50 to the implant by applying some force. Inanother embodiment, a dovetail-type connection, such that placement ofdistal end 70 over the implant with rotation should couple the innersleeve 50 to the implant, thus preventing separation. Other suitablemechanisms may be used to prevent separation of distal end 70 from theimplant. The implant may include any of a variety of surgical implantsthat may be secured to a vertebral body, including, for example, a spinestabilization system that includes a bone fastener (e.g., a pediclescrew) coupled to a rod. By way of example, distal end 70 may fit overthe head of the bone fastener. Distal end 70 may include slots 90through which the rod extends when distal end 70 is fitted over the bonefastener, for example. Distal end 70 may further include a beveledsurface 100.

Inner sleeve 50 may further include locking mechanisms 110 that extendradially from inner sleeve 50 opposite distal end 70. Locking mechanisms110 may each include a stop 120, actuator 130, and guide 140. Asillustrated, the stop 120 and actuator 130 may be on either end of theguide 140 with the guide 140, for example, being a pin or rod extendingbetween stop 120 and actuator 130. Pressing down on actuator 130 shouldcause locking mechanisms 110 to depress towards inner sleeve 50.

Referring now to FIGS. 1-5, outer sleeve 60 will be described in moredetail in accordance with one embodiment of the present invention. Aspreviously mentioned, outer sleeve 60 may be disposed over inner sleeve50. Outer sleeve 60 may comprise a first opening 150 and a secondopening 160 connected by channel 170. While not illustrated, outersleeve 60 further may comprise corresponding openings to first opening150, second opening 160, and channel 170, on the opposite side of outersleeve. First opening 150 and second opening 160 should each have agreater width than channel 170. Second opening 160 should be closer toproximal end 175 of outer sleeve 60 than first opening 150. Channel 170should generally be dimensioned to allow passage of guide 140 of lockingmechanisms 110, but should not be of sufficient size for passage of stop120, when tube assembly 20 is assembled. First opening 150 and secondopening 160 should be dimensioned to allow penetration of stop 120.Outer sleeve 60 further may comprise additional openings, such as thirdopening 180 and fourth opening 190. These additional openings shouldprovide access to inner sleeve 50 after assembly of tube assembly 20,for example, so that interior components of tube assembly 20 may beinspected and/or cleaned as desired. In an embodiment, outer sleevefurther comprises a chamfered distal end 210.

As illustrated by FIGS. 2 and 3, shaft 200 may be coupled to outersleeve 60 in accordance with one embodiment of the present invention. Ingeneral, shaft 200 may extend axially from proximal end 175 of outersleeve 60. In an embodiment, shaft 200 and outer sleeve 60 may be aunitary piece. In an alternative embodiment (not illustrated), shaft 200may be attached to outer sleeve by any suitable mechanism, such as by abolted and/or threaded connection. As illustrated, shaft may have asquare-shaped proximal end 430. While proximal end 430 of shaft 200 isillustrated as generally square in shape other shapes (e.g., circular)may also be suitable in accordance with embodiments of the presentinvention.

FIGS. 4 and 5 illustrate operation of the locking mechanisms 110 of tubeassembly 20 in accordance with one embodiment of the present invention.As will be described below, locking mechanisms 110 may be used to couplederotation apparatus 10 to the implant (not illustrated). The followingdescription is with respect to movement of one of locking mechanisms 110from an unlocked to a locked position. However, it should be understoodthat the illustrated embodiment contains two locking mechanisms 110 withboth locking mechanisms 110 functioning in a similar manner toeffectuate locking and unlocking of tube assembly 20.

FIG. 4 illustrates tube assembly 20 with locking mechanism 110 in anunlocked position in accordance with one embodiment of the presentinvention. As illustrated, when tube assembly 20 is unlocked, outersleeve 60 may be disposed over inner sleeve 50 with distal end 70 ofinner sleeve 50 uncovered. In an embodiment, when unlocked, lockingmechanism 110 should extend through first opening 150 in outer sleeve60. Block 120 may be positioned in first opening 150 so that lockingmechanism 110 is engaged with first opening 150, preventing movement oflocking mechanism 110. This should fix the position of inner sleeve 50with respect to outer sleeve 60. When in the unlocked position, distalend 70 of inner sleeve 50 may be placed over at least a portion of animplant (not illustrated). Various mechanism may be applied so that thederotation apparatus 10 is prevented from separating from the distal end70 of the implant.

FIG. 5 illustrates tube assembly 20 with locking mechanism 110 in alocked position in accordance with one embodiment of the presentinvention. The tube assembly 20 may be placed in the locked position tofurther secure the inner sleeve 50 onto the implant. To place thelocking mechanism 110 in a locked position in accordance with oneembodiment, actuator 130 should be pressed causing locking mechanism 110to depress towards inner sleeve 50. Stop 120 may move completely throughfirst opening 150 so that stop 120 disengages with first opening 150.With locking mechanism 110 depressed, pressure should be applied to tubeassembly 20 forcing outer sleeve 60 further down onto inner sleeve 50.As outer sleeve 60 passes down onto inner sleeve 50, guide 140 shouldpass through channel 170 until locking mechanism 110 reaches secondopening 160. Actuator 130 should then be released so that lockingmechanism 110 raises and engages with second opening 160 with stop 120preventing movement. As outer sleeve 60 is forced down onto first sleeve50, chamfered distal end 210 of outer sleeve 60 passes over beveledsurface 100. This forces the outer sleeve 60 against distal end 70 ofinner sleeve 50 pressing distal end 70 tighter against the implant (notillustrated). This tightening force should clamp distal end 70 onto theimplant preventing separation of distal end 70 from the implant.Accordingly, in this manner, derotation apparatus 10 can be securelyconnected to an implant. Other suitable mechanisms for securingderotation apparatus 10 onto an implant may also be used in accordancewith embodiments of the present invention.

Derotation apparatus 10 may further comprise ball joint assembly 30. Ingeneral, ball joint assembly 30 should be configured and adapted tocouple derotation apparatus 10 to least one additional derotationapparatus 10. As discussed below with respect to FIGS. 12-14, two ormore derotation apparatuses 10 may be linked by at least one couplingrod 220 forming a coupled derotation system 225. Referring now to FIGS.1 and 2, ball joint assembly 30 may comprise at least one ball joint 80.In an embodiment, at least one ball joint 80 may be a spring-loaded balljoint. In general, each of at least one ball joint 80 may be rotatable.For example, each of at least one ball joint 80 should be rotatableabout at least one axis and, preferably, at least two axes. In anembodiment illustrated by FIG. 6, each of at least one ball joint 80 maybe rotated about z-axis 230. For example, at least one ball joint 80 mayrotate about z-axis 230 by an angle of up to about 360°. As illustrated,the two ball joints 80 may have an angle of rotation of about 90° withrespect to one another. In an embodiment illustrated by FIG. 7, at leastone ball joint 80 may be rotated about a y-axis (not illustrated), whichwould extend in a direction perpendicular to the figure. For example, atleast one ball joint 80 may rotate about the y-axis by an angle (θ) ofup to about 360°. As illustrated, one of the ball joints 80 may rotateabout the y-axis by an angle (θ) of at least about 20°.

Referring now to FIGS. 2, 8 and 9, ball joint assembly 30 will bedescribed in more detail with respect to one embodiment of the presentinvention. As illustrated, ball joint assembly 30 comprises at least oneball joint 80. Each ball joint 80 may comprise a ball 240 containedwithin a housing 250 with ball 240 and housing 250 disposed on shaft200. In an embodiment, ball 240 is formed by upper portion 260 and lowerportion 270 that when matched together form ball 240. Upper portion 260and lower portion 270 may each be generally annularly shaped so thateach portion can fit onto shaft 200. As illustrated, upper portion 260may be a separate piece that forms the top half of ball 240 while lowerportion 270 may be a separate piece that forms the lower half of ball240. In an embodiment (not illustrated), upper portion 260 and lowerportion 270 are unitary pieces or, alternatively, coupled in somemanner. Each of upper portion 260 and lower portion 270 may comprise ahole, such as tapered through hole 275 to, for example, facilitaterotation of at least one ball joint 80 on shaft 200. In an embodiment,upper portion 260 and lower portion 270 of each ball joint 80 maycomprise serrated ball edges 285 on at least a portion of theirrespective exterior surfaces forming the outer surface of respectiveball 240.

In the illustrated embodiment, each of upper portion 260 and lowerportion 270 comprises a tab, for example, upper tab 280 and lower tab290. Upper tab 280 and lower tab 290 may extend radially and outwardlyfrom upper portion 260 and lower portion 270, respectively. Together theupper tab 280 and lower tab 290 may be configured and adapted to form aclamp 300 that grips coupling rod 220 (illustrated on FIGS. 12-14). Inthis manner, each ball joint 80 may retain a corresponding coupling rod220. In an embodiment, clamp 300 formed by upper tab 280 and lower tab290 is open, for example, to facilitate insertion of coupling rod 220.In an embodiment, clamp 300 is generally u-shaped. As illustrated, thefacing surfaces 310 of upper tab 280 and lower tab 290 may be rounded sothat upper tab 280 and lower tab 290 form rod opening 315 for receivingcoupling rod 220.

As illustrated by FIGS. 2, 8, and 9, each one ball joint 80 further maycomprise inner washers 320 and outer washers 330 that are each disposedover shaft 200, in accordance with one embodiment of the presentinvention. Inner washers 320 and outer washers 330 may each comprise acentral opening (not illustrated) that is dimensioned for shaft 200 tofit through. Inner washers 320 may each comprise a protruding rim 340with a rounded surface 350. In an embodiment, rounded surface 350 may besmooth to allow for rotation of ball 240. Inner washers 320 also mayeach comprise an outer shoulder 360. As illustrated, outer shoulder 360of each of inner washers 320 may be inwardly facing, in that outershoulder 360 may face ball 240 of the respective ball joint 80. Innerwashers 320 further may each comprise an inner spring shoulder 370facing in the opposite direction of outer shoulder 360. Outer washers330 may each comprise an inner shoulder 380. This inner shoulder 380 isoutwardly facing because it faces away from ball 240. In an embodiment,one or more of outer washers 330 may be integral with housing 250. Asillustrated by FIG. 8, this integral washer of outer washers 330 may bethe uppermost of outer washers 330, in accordance with one embodiment.In an alternative embodiment (not illustrated), each of outer washers330 may be separate pieces from housing 250. As illustrated by FIG. 9,the lowermost of outer washers 330 may be separate from housing 250 inaccordance with one embodiment. In an embodiment, one or more of outerwashers 330 may each comprise one or more serrated edges. In theillustrated embodiment, each of outer washers 330 may comprise innerserrated edge 390 and outer serrated edge 400. As illustrated, innerserrated edge 390 may be rounded for mating with ball 240.

Each ball joint 80 may further comprise springs 405. As illustrated,springs 405 may be disposed over shaft 200 on either side of innerwashers 320. In an embodiment, springs 405 are compression springs. Inan embodiment, each ball joint 80 may share one of springs 405. In theillustrated embodiment, each ball joint 80 comprises two springs 80 witheach ball joint sharing one of springs 80. In an alternative embodiment(not illustrated), each of at least one ball joint 80 may comprise onecompression spring.

Referring now to FIGS. 1 and 2, handle assembly 40 will be described inmore detail, in accordance with one embodiment of the present invention.In the illustrated embodiment, handle assembly 40 comprises handle 410and cap 420. Handle 410 may be generally tubular in shape with apassageway extending longitudinally therethrough. As illustrated, handle410 may comprise lower tubular section 440 and upper tubular section450. In an embodiment, lower tubular section 440 may have an innerdiameter than is smaller than the inner diameter of upper tubularsection 450. In an embodiment (not illustrated), lower tubular section440 may have inner threads. When derotation apparatus 10 is assembled,shaft 200 may be received into lower tubular section 440. One or moreholes 460 may be formed in upper tubular section 440. Handle 410 furthermay comprise inner cap shoulder 470, for example, at the intersection oflower tubular section 440 and upper tubular section 450. As illustrated,interior cap shoulder 470 may be upwardly facing.

In an embodiment, cap 420 may be configured and adapted to lock handle410 on derotation apparatus 10. As illustrated, cap 420 may comprisehead 480, elongated shaft 490, and exterior threads 500. When derotationapparatus 10 is assembled, for example, cap 420 may be disposed in theinterior of handle 410 with cap 420 engaging inner cap shoulder 470 ofhandle 410 and elongated shaft 490 extending down into lower tubularsection 440. While not illustrated, cap 420 may include features to lockinto handle 410. In an embodiment (not illustrated), cap 420 may bethread into lower tubular section 440 of handle 410. For example,exterior threads 500 of cap 420 may thread into interior threads (notillustrated) in lower tubular section 440. In addition, cap 420 may alsoinclude features to secure handle 410 and ball joint assembly 30 onshaft 200. For example, cap 420 may be disposed over proximal end 430 ofshaft 200 with screw 520 inserted into threaded hole 510 of cap 420 toengage shaft 200. As illustrated, threaded hole 510 may be in head 480of cap 420. In an embodiment, elongated shaft 490 may have arectangularly shaped opening 505 into which square-shaped proximal end430 of shaft 200 may be inserted. It should be understood that othershaped openings in elongated shaft 490 may also be suitable for use inembodiments of the present invention. With cap 420 secured onto shaft200, handle 410 may be rotated to, for example, tighten handle 410 downonto shaft 200, thus tightening handle 410 down onto ball joint assembly30. The preceding description describes handle assembly 40 that can beused in accordance with an embodiment of the present invention. However,it should be understood that other suitable assemblies for tighteningdown onto ball joint assembly 30 can be used in accordance withembodiments of the present invention.

Referring now to FIG. 10, ball joint 80 is illustrated in an unlockedposition in accordance with one embodiment of the present invention. Asillustrated, outer washers 330 may be located on either side of ball240. As previously described, ball 240 may be formed by upper portion260 and lower portion 270 that match together to form ball 240. In theillustrated embodiment, the uppermost of outer washers 330 is integralwith housing 250 with the lowermost of outer washers 330 slidablydisposed within housing 250. Inner washers 320 may also be located oneither side of ball 240. Outer shoulder 360 of each of inner washers 320should engage corresponding inner shoulder 380 of outer washers 330. Asillustrated, protruding rim 340 of each of inner washers 320 may extendthrough a corresponding one of outer washers 330. Rounded surface 350 ofprotruding rim 340 of each of inner washers 320 may contact ball 240. Aspreviously mentioned, rounded surface 350 may be smooth to allow forrotation of ball 240. As illustrated, springs 405 may be located oneither side of inner washers 320. In the illustrated embodiment, springs405 engage inner spring shoulder 370 of inner washers 320. In anembodiment, springs 405 may force outer shoulder 360 of each innerwasher 320 into engagement with inner shoulder 380 of each outer washer330.

Referring now to FIG. 11, ball joint 80 is illustrated in a lockedposition in accordance with one embodiment of the present invention.Ball joint 80 may be placed in a locked position to secure coupling rod220 in clamp 300 (illustrated on FIGS. 12-14). To place ball joint 80 ina locked position in accordance with one embodiment, handle assembly 40may be tightened down onto ball joint assembly 30, for example. As thehandle assembly 40 is tightened, inner washers 320 may be pushed insideof outer washers 330 so that protruding rim 340 no longer extendsthrough outer washers 330. The outer washers 330 may then engage ball240 with springs 405 forcing upper portion 260 and lower portion 270together. By forcing upper portion 260 and lower portion 270 together,clamp 300 may be closed onto a coupling rod 220 (illustrated on FIGS.12-14). In addition, engagement of outer washers 330 with ball 240 mayalso prevent rotation of ball 240. As previously mentioned, outerwashers 330 and/or outer surfaces 240 of ball 240 may be serrated. In anembodiment, inner serrated edge 390 of each outer washer 330 engagesserrated ball edges 285 to prevent rotation of ball 240. The precedingdescription describes one suitable technique for locking ball joint 80to prevent rotation of ball 240 and secure coupling rod 220 in clamp300. However, it should be understood that other suitable techniques forpreventing rotation of ball 240 and for securing coupling rod 220 inclamp 300 can be used in accordance with embodiments of the presentinvention.

One or more derotation apparatuses 10 may be used in the treatment ofspinal irregularities in accordance with embodiments of the presentinvention. For example, derotation apparatus 10 may be used to derotatea vertebral body, thus reducing rotation between vertebral bodies in apatient's spine. Derotation of the vertebral body with derotationapparatus 10 may also straighten curvature of the spine. In anembodiment, derotation apparatus 10 may be used in conjunction with animplant (e.g., a bone fastener coupled to a rod) to also addresscurvature of the spine. An embodiment of treating a spinal irregularitymay include coupling derotation apparatus 10 to an implant. In anembodiment, the implant may be attached to a vertebral body. Couplingderotation apparatus 10 to an implant may include, for example,placement of distal end 70 of inner sleeve 50 over implant. In anembodiment, distal end 70 may be placed over implant to preventseparation of inner sleeve from implant. Coupling derotation apparatus10 to implant further may include placing tube assembly 20 into a lockedposition to further secure inner sleeve 50 onto implant. In anembodiment, in the locked position, outer sleeve 60 may be disposed overdistal end 70 of inner sleeve 50, clamping distal end 70 onto theimplant. After securing the inner sleeve 50 on the implant, force may beapplied to handle assembly 40 to derotate the vertebral body to whichthe implant is attached.

Embodiments for treating a spinal irregularity further may includecoupling derotation apparatus 10 to at least one additional derotationapparatus 10 to form a coupled derotation system 225. For example, balljoints 80 in separate derotation apparatus 10 may be aligned so that acoupling rod 220 may be placed into a corresponding clamp 300 of thealigned ball joints 80. To lock the coupling rod 220 in place, thealigned ball joints 80 may then be placed in a locked position, forexample, by tightening of a corresponding handle assembly 40. It shouldbe understood that each derotation apparatus 10 in coupled derotationsystem 225 may be coupled to a corresponding implant. Force may beapplied to handle assembly 40 in at least one derotation apparatus 10 incoupled derotation system 225. In an embodiment, force may be applied tohandle assembly 40 of each derotation apparatus 10 in coupled derotationsystem 225. Application of force to handle assembly 40 should derotatethe vertebral bodies to which coupled derotation system 225 is attached.

Referring now to FIG. 12, coupled derotation system 225 for treatment ofspinal irregularities is illustrated in accordance with one embodimentof the present invention. As illustrated, coupled derotation system 225includes two derotation apparatuses 10 interconnected by coupling rod220. In the illustrated embodiment, derotation apparatuses 10 areconnected to bone fasteners 530 on either side of vertebral body 540.Rotational force applied to vertebral body 540 should be distributedbetween bone fasteners 530. As illustrated, bone fasteners 530 may be acomponent of a bone fixation system 550 for fusing spine 560 that mayinclude a single rod or a pair of parallel rods 570.

Referring now to FIG. 13, an embodiment of coupled derotation system 225for treatment of spinal irregularities is illustrated in which threederotation apparatuses 10 interconnected by coupling rod 220 areconnected to bone fasteners 530 on the same side of spine 560. In anembodiment, derotation apparatuses 10 may be connected to vertebralbodies 540 at the apex of the curvature of spine 560. This arrangementof derotation apparatuses 10 should distribute force across multiplelevels of spine 560.

Referring now to FIG. 14, an embodiment of coupled derotation system 225for treatment of spinal irregularities is illustrated in which multiplederotation apparatuses 10 are interconnected by coupling rods 220. Asillustrated, derotation apparatuses 10 may be coupled to bone fasteners530 over multiple levels of spine 560 and on both sides of spine 560.This arrangement of derotation apparatuses 10 should distribute forceacross multiple levels of spine 560 for derotation of vertebral bodies540.

While it is apparent that the invention disclosed herein is wellcalculated to fulfill the objects stated above, it will be appreciatedthat numerous modifications and embodiments may be devised by thoseskilled in the art.

What is claimed is:
 1. An apparatus for treating spinal irregularities,comprising: a derotation apparatus comprising: a tube assemblycomprising an inner sleeve and an outer sleeve disposed over the innersleeve, wherein the inner sleeve has a distal end for attachment to animplant; a handle assembly; and a ball joint assembly disposed betweenthe tube assembly and the handle assembly, wherein the ball jointassembly comprises a ball joint configured for attachment to a couplingrod wherein the ball joint comprises a spring capable of applyingpressure to the ball to lock the ball and secure the connecting rod inthe clamp.
 2. The apparatus of claim 1, wherein the outer sleeve iscapable of sliding down onto a distal end of the inner sleeve to engagethe inner sleeve and clamp the distal end on the implant.
 3. Theapparatus of claim 1, wherein the derotation apparatus comprises alocking mechanism capable of securing the tube assembly on the implant,the locking mechanism extending radially from the inner sleeve andcomprising a stop, an actuator, and a guide extending between the stopand the actuator.
 4. The apparatus of claim 3: wherein the outer sleevecomprises a first opening, a second opening located closer to a proximalend of the outer sleeve than the first opening, and a channel connectingthe first opening and the second opening; wherein the locking mechanismis configured to extend through a first opening in the outer sleeve withthe stop engaging the outer sleeve, when the tube assembly is in anunlocked position; and wherein the locking mechanism is configured toextend through a second opening, with the stop engaging the outersleeve, when the tube assembly is in a locked position.
 5. The apparatusof claim 1, wherein the ball joint comprises an upper portion and alower portion that match together to form a rotatable ball, the upperportion comprising a radially extending upper tab, the lower portioncomprising a radially extending lower tab, and the upper tab and thelower tab forming a clamp for receiving the connecting rod.
 6. Theapparatus of claim 5, wherein the ball joint is a spring-loaded balljoint that comprises: an outer washer having a serrated surface, whereinthe serrated surface is configured to prevent rotation of the ball byengaging an outer surface of the ball when the ball joint is in a lockedposition; and an inner washer fit within the outer washer and having aprotruding rim with a smooth surface, and wherein the protruding rim isconfigured to extend through the outer washer to engage smooth surfaceto extend through the outer washer engage an outer surface of the ballwithout preventing rotation of the ball when the ball joint is in anunlocked position.
 7. The apparatus of claim 5, wherein the handleassembly comprises a handle, and wherein the clamp is configured toclose down onto the coupling rod upon tightening of the handle onto theball joint assembly.
 8. The apparatus of claim 1, wherein the ball jointassembly comprises a second ball joint configured for attachment to asecond coupling rod.
 9. The apparatus of claim 1, wherein the handleassembly comprises a handle capable of tightening down onto the balljoint assembly to lock the ball joint.
 10. The apparatus of claim 1,wherein the apparatus comprises: a second derotation apparatuscomprising: a tube assembly comprising an inner sleeve and an outersleeve disposed over the inner sleeve, wherein the inner sleeve has adistal end for attachment to a second implant; a handle assembly; and aball joint assembly disposed between the tube assembly and the handleassembly, wherein the ball joint assembly comprises a ball joint coupledto the ball joint of the first derotation apparatus by the connectingrod.
 11. The apparatus of claim 10, wherein the apparatus comprises: athird derotation apparatus comprising: a tube assembly comprising aninner sleeve and an outer sleeve disposed over the inner sleeve, whereinthe inner sleeve has a distal end for attachment to a third implant; ahandle assembly; and a ball joint assembly disposed between the tubeassembly and the handle assembly, wherein the ball joint assemblycomprises a ball joint coupled to the connecting rod.
 12. The apparatusof claim 10, wherein ball joint assembly of the first derotationapparatus comprises a second ball joint, and wherein the apparatuscomprises: a third derotation apparatus comprising: a tube assemblycomprising an inner sleeve and an outer sleeve disposed over the innersleeve, wherein the inner sleeve has a distal end for attachment to athird implant; a handle assembly; and a ball joint assembly disposedbetween the tube assembly and the handle assembly, wherein the balljoint assembly comprises a ball joint coupled to the second ball jointof the first derotation apparatus by the second coupling rod.
 13. Aderotation apparatus comprising: a tube assembly comprising an innersleeve, an outer sleeve disposed over the inner sleeve, and a shaftextending from a proximal end of the outer sleeve, wherein the innersleeve comprises a distal end for attachment to an implant, and alocking mechanism capable of securing the distal end of the inner sleeveto the implant and a ball joint assembly disposed on the shaft betweenthe handle assembly and the tube assembly, wherein the ball jointassembly comprises: a first ball joint comprising: a housing; a ballwithin the housing that comprises an upper portion having a radiallyextending upper tab, and a separate lower portion having a radiallyextending lower tab, wherein the upper tab and the lower tab form aclamp for receiving a connecting rod; a second ball joint comprising: ahousing; a ball within the housing that comprises an upper portionhaving a radially extending upper tab, and a separate lower portionhaving a radially extending lower tab, wherein the upper tab and thelower tab form a clamp for receiving a connecting rod.
 14. An apparatusfor treating spinal irregularities, comprising: a derotation apparatuscomprising: a tube assembly comprising an inner sleeve and an outersleeve disposed over the inner sleeve, wherein the inner sleeve has adistal end for attachment to an implant; a handle assembly; and a balljoint assembly disposed between the tube assembly and the handleassembly, wherein the ball joint assembly comprises a ball jointconfigured for attachment to a coupling rod, wherein the ball jointcomprises an upper portion and a lower portion that match together toform a rotatable ball
 15. The apparatus of claim 14, wherein the outersleeve is capable of sliding down onto a distal end of the inner sleeveto engage the inner sleeve and clamp the distal end on the implant. 16.The apparatus of claim 14, wherein the derotation apparatus comprises alocking mechanism capable of securing the tube assembly on the implant,the locking mechanism extending radially from the inner sleeve andcomprising a stop, an actuator, and a guide extending between the stopand the actuator.
 17. The apparatus of claim 14: wherein the outersleeve comprises a first opening, a second opening located closer to aproximal end of the outer sleeve than the first opening, and a channelconnecting the first opening and the second opening; wherein the lockingmechanism is configured to extend through a first opening in the outersleeve with the stop engaging the outer sleeve, when the tube assemblyis in an unlocked position; and wherein the locking mechanism isconfigured to extend through a second opening, with the stop engagingthe outer sleeve, when the tube assembly is in a locked position.